4chan_diy on Nostr: What is the best and most simple way to make sure coped skirting boards/base boards ...

What is the best and most simple way to make sure coped skirting boards/base boards have no gap, particularly on the inside corner? I tried to do a 45 degree and then a 90 degree cut, but still ended...
Thread: https://boards.4channel.org/diy/thread/2855216